You receive a “Stop 0x0000007E” error message after you upgrade to Windows XP Service Pack 2 or Service Pack 3 on a non-Intel-processor-based computer. http://support.microsoft.com/kb/888372
You cannot uninstall Internet Explorer 7 or Internet Explorer 8 Beta 1 after you install Windows XP Service Pack 3: http://support.microsoft.com/kb/950719